This invention relates generally to mirrors for vehicles, more particularly to rear vision mirrors providing a wide-angle view from either outer side of the vehicle and through the blind spot that is not imaged by conventional rear view mirrors, the mirror itself consisting essentially of a single generally planar reflective surface and a single contoured reflective surface while avoiding the use of any generally spherically shaped reflective surfaces.
Rear vision mirrors that include generally convex reflective areas for providing a reflective view intended to be more extensive than that which can be provided by a flat reflective area are shown for example in U.S. Letters Pat. No. 3,764,201, which discloses a rear vision mirror expressly designed and adapted for large trucks and buses. This patent includes the use of spherical reflective surfaces. The presence of spherical surfaces necessitates, by statute, that a rear view mirror spherical reflective surface have a radius of at least 20 inches in order to preclude image distortion and vehicle operator confusion brought about by a spherical reflective surface having a radius less than 20 inches. Mirrors in compliance with this statutory requirement are exceedingly large and unsuitable for use in smaller vehicles such as passenger automobiles, vans and pick-up trucks having limited side window height and practical limits of how far an outside-mounted mirror can reasonably project beyond the width of these smaller vehicles.
Additionally, U.S. Pat. No. 3,764,201 specifies convex generally cylindrical reflecting zones or areas that curve rearwardly and that have a radius of 5 inches. With the present invention, it has been discovered that a generally convex cylindrical reflecting surface having a radius as small as on the order of 5 inches is not satisfactory because such a small radius creates an unsafe amount of image distortion that all too often leads to driver confusion, especially for non-professional drivers who typically operate passenger automobiles and the like. A radius as small as about 5 inches or less causes a deceiving and very abrupt change in the image seen in the reflective surface, particularly at the junction of the curved reflective surface and an adjacent flat reflective surface.
By the present invention, the disadvantages attendent to using spherically contoured reflective surfaces are avoided, as is the need to use exceptionally large reflective surfaces or the practice of utilizing reflective surfaces having curvature radii smaller than that now found to enhance the safe use of combined curved and planar reflective surfaces, particularly by non-professional drivers. The present invention avoids distortions brought about by spherical surfaces and by curved reflective surfaces having small radii, while at the same time avoiding the need to provide rear vision mirrors having a size that is prohibitive for smaller vehicles such as passenger automobiles and the like.
The present invention provides a wide-angle rear vision mirror that has a single contoured surface which is not spherically contoured and which is integral with and outwardly extending from a single substantially planar reflective surface, wherein the single contoured surface is a convex cylindrically contoured surface having a radius of curvature of approximately 8 inches, plus or minus about 121/2 percent.
It is accordingly a general object of the present invention to provide an improved rear vision mirror.
Another object of this invention is an improved rear vision mirror especially structured for mounting outside of either the left side window or the right side window of a vehicle.
Another object of the present invention is an improved rear view or rear vision mirror having a structure that avoids significant image distortion brought about by spherical reflective surfaces and/or contoured surfaces having radii outside of a critical range of radii values.
Another object of the present invention is an improved rear vision mirror for use on relatively small vehicles such as passenger automobiles in order to provide an image at the blind spot area without substantially distorting such image.
Another object of the present invention is an improved rear vision mirror having a single generally planar reflective surface and a single generally cylindrically contoured reflective surface, which surfaces have area measurements related to each other in a predetermined manner.